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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
//! Computed types for CSS Easing functions.
use euclid::approxeq::ApproxEq;
use crate::bezier::Bezier;
use crate::piecewise_linear::PiecewiseLinearFunction;
use crate::values::computed::{Integer, Number};
use crate::values::generics::easing::{self, BeforeFlag, StepPosition, TimingKeyword};
/// A computed timing function.
pub type ComputedTimingFunction = easing::TimingFunction<Integer, Number, PiecewiseLinearFunction>;
/// An alias of the computed timing function.
pub type TimingFunction = ComputedTimingFunction;
impl ComputedTimingFunction {
fn calculate_step_output(
steps: i32,
pos: StepPosition,
progress: f64,
before_flag: BeforeFlag,
) -> f64 {
// User specified values can cause overflow (bug 1706157). Increments/decrements
// should be gravefully handled.
let mut current_step = (progress * (steps as f64)).floor() as i32;
// Increment current step if it is jump-start or start.
if pos == StepPosition::Start ||
pos == StepPosition::JumpStart ||
pos == StepPosition::JumpBoth
{
current_step = current_step.checked_add(1).unwrap_or(current_step);
}
// If the "before flag" is set and we are at a transition point,
// drop back a step
if before_flag == BeforeFlag::Set &&
(progress * steps as f64).rem_euclid(1.0).approx_eq(&0.0)
{
current_step = current_step.checked_sub(1).unwrap_or(current_step);
}
// We should not produce a result outside [0, 1] unless we have an
// input outside that range. This takes care of steps that would otherwise
// occur at boundaries.
if progress >= 0.0 && current_step < 0 {
current_step = 0;
}
// |jumps| should always be in [1, i32::MAX].
let jumps = if pos == StepPosition::JumpBoth {
steps.checked_add(1).unwrap_or(steps)
} else if pos == StepPosition::JumpNone {
steps.checked_sub(1).unwrap_or(steps)
} else {
steps
};
if progress <= 1.0 && current_step > jumps {
current_step = jumps;
}
(current_step as f64) / (jumps as f64)
}
/// The output of the timing function given the progress ratio of this animation.
pub fn calculate_output(&self, progress: f64, before_flag: BeforeFlag, epsilon: f64) -> f64 {
match self {
TimingFunction::CubicBezier { x1, y1, x2, y2 } => {
Bezier::calculate_bezier_output(progress, epsilon, *x1, *y1, *x2, *y2)
},
TimingFunction::Steps(steps, pos) => {
Self::calculate_step_output(*steps, *pos, progress, before_flag)
},
TimingFunction::LinearFunction(function) => function.at(progress as f32).into(),
TimingFunction::Keyword(keyword) => match keyword {
TimingKeyword::Linear => return progress,
TimingKeyword::Ease => {
Bezier::calculate_bezier_output(progress, epsilon, 0.25, 0.1, 0.25, 1.)
},
TimingKeyword::EaseIn => {
Bezier::calculate_bezier_output(progress, epsilon, 0.42, 0., 1., 1.)
},
TimingKeyword::EaseOut => {
Bezier::calculate_bezier_output(progress, epsilon, 0., 0., 0.58, 1.)
},
TimingKeyword::EaseInOut => {
Bezier::calculate_bezier_output(progress, epsilon, 0.42, 0., 0.58, 1.)
},
},
}
}
}
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